KR19980077061A - How to control yaw motion of vehicle active steering - Google Patents

Abstract

The present invention relates to a method of controlling a yaw motion of a vehicle active steering apparatus, and in the related art, since the steering of a mechanical steering apparatus is totally dependent on the steering of a driver, there is a problem in that yaw motion that can be caused by a large- there was.

As shown in FIG. 3, the lateral acceleration of the vehicle, which is a cause of the lateral motion of the vehicle, is transmitted to the front wheel So that the controller can determine the steering angle that excludes the yaw rate from the lateral slip angle.

Therefore, when the disturbance occurs, the yawing motion is suppressed and the driving trajectory is maintained, so that the driving stability of the vehicle is improved.

Description

How to control yaw motion of vehicle active steering

The present invention relates to a yawing motion control method for a vehicle active steering apparatus, and more particularly, to a yawing motion control method for a yawing motion control apparatus for a yawing yawing motion of a vehicle by determining a steering angle of a controller that excludes yaw rate at a lateral slip angle, To a yawing motion control method for a vehicle active steering system in which a yawing motion of a vehicle is suppressed.

The steering apparatus for arbitrarily changing the traveling direction of the vehicle can be largely divided into an operating mechanism, a gear mechanism, and a link mechanism.

That is, as shown in Fig. 1 (a), the operating mechanism is a mechanism that the driver directly performs a steering operation to transmit the operating force to the gear mechanism and the link mechanism, and is constituted by the steering wheel 1, the steering shaft 2 .

The gear mechanism increases the operating force by reducing the rotation of the steering shaft and changes the direction of movement of the operating mechanism to transmit the operating mechanism to the link mechanism. The gear mechanism is a gear mechanism fixed to the frame.

The link mechanism is a mechanism that transmits the movement of the gear mechanism to the front wheels and maintains the relative positions of the right and left front wheels correctly. The link mechanism is composed of a footmember 3, a relay rod 4, a tie rod 5, a knuckle arm 6 Consists of.

Therefore, when the driver turns the steering wheel 1, the rotational motion is transmitted to the steering gear via the steering shaft 2. [

The rotational motion transmitted to the steering gear is converted to a linear or pivotal motion according to the gear type together with the deceleration, and this is transmitted through the link mechanism to steer the front wheel.

Here, there are many gear mechanisms, such as a rack pinion, a worm sector roller, and a circular ball type, depending on the gear type. FIG. 1 (B) shows a rack pinion type gear mechanism.

In the gear mechanism of the rack pinion type, a pinion 7 is formed on the steering shaft 2, and a rack 8 linked to the pinion 7 is engaged with the link mechanism so that the rotational motion of the steering wheel 1 is converted into a linear motion have.

Such a rack-pinion type gear mechanism is small and lightweight and can be installed at a low height, and is mainly employed in compact cars.

However, such a steering apparatus can not be expected to have an ideal steering characteristic according to the motion characteristics of the vehicle body.

That is, as described above, the steering device is a mechanical power transmission device, and the operating mechanism, the gear mechanism, and the link mechanism are mechanically coupled, and the control thereof is entirely dependent on the steering wheel operation of the driver.

On the other hand, steering by this steering device causes yaw motion and lateral motion, which are rotational motions in the vertical axis of the vehicle center, and that the lateral motion follows the intended trajectory of the driver He is in charge of leading role.

However, since the yawing motion and the lateral motion are linked with each other due to the motion characteristics, yawing motion occurs in the vehicle due to the disturbance such as the state of the road surface or the wind power. At this time, when the steering wheel is manipulated by the driver, There is a possibility that a major accident occurs because it is affected by motion.

In order to solve such a problem, a steering shaft coupled to a steering wheel and a gear mechanism is currently being developed in an ambitious manner, and the steering unit of the steering wheel is controlled based on the steering wheel operation of the driver, And it is an object of the present invention to provide a yawing motion control method of a vehicle steering apparatus applied to the active steering system.

The present invention for this purpose is based on the fact that the lateral acceleration of the vehicle, which is a factor of the lateral motion of the vehicle, is related to the lateral slip angle of the front wheel, so that the controller can determine the steering angle that excludes the yaw rate at such lateral slip angle.

Therefore, when the disturbance occurs, the yawing motion is suppressed and the driving trajectory is maintained, so that the driving stability of the vehicle is improved.

1 (A) and 1 (B) are diagrams showing a conventional mechanical steering apparatus,

2 (a) and 2 (b) are conceptual diagrams showing a yawing motion control method according to the present invention,

3 is a block diagram illustrating the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings.

The present invention relates to a front wheel steering angle control system ) Is sufficiently small, the position at which the lateral force of the rear wheel is excluded ( ), The lateral force of the vehicle corresponds to the lateral slip angle of the front wheel The lateral force of the front wheel ) ≪ / RTI > of the vehicle < RTI ID = 0.0 & ), And the lateral sliding angular velocity of the front wheel ( ) Is the steering angle velocity of the driver ) And the steering angle velocity of the controller ( ) And the sliding angular velocity of the front wheel chassis ), And the lateral slip angle ( Is independent of the yaw rate?, The lateral acceleration? ) Is independent of the yaw rate (?), The lateral slip angular velocity The steering angle velocity of the controller in which the yaw rate (?) Component is excluded ), And the integral value thereof is set to the steering angle of the controller ) Of the vehicle.

FIG. 2 is a conceptual diagram illustrating a method of controlling yaw motion of a vehicle active steering apparatus according to the present invention. In the present invention, a controller of an active steering apparatus controls a yaw motion that can not be controlled by a driver during a disturbance operation while the vehicle is running.

In other words, as described above, the vehicle steering performed by the driver causes yaw motions and lettering motions. By separating the yaw motions from the letter motions and giving the steering angles excluding the yaw motions to the controller, The yaw motion of the vehicle is suppressed.

First, a position that is not affected by the lateral force of the rear wheel The lateral acceleration of the vehicle .

here, Lt;

Is the rotational inertia moment from the center of gravity CG,

Is the vehicle weight,

Is the distance between the center of gravity CG and the center of the rear wheel.

Therefore, the lateral acceleration at l _p .

here, Is the lateral force of the vehicle, Is the steering angle of the front wheel.

On the other hand, the lateral force of the front wheel is the lateral slip angle , And when the disturbance during the straight running is applied, the front wheel steering angle < RTI ID = 0.0 > Is sufficiently small, the lateral force of the vehicle The lateral force of the front wheel .

Therefore, .

Here, the lateral acceleration a _yp, which determines the lateral motion, Is independent of the yaw rate?, The lateral slip angle?

That is, the lateral slip angle independent of the yaw rate And based on this, the controller can give the steering angle in which there is only the letter motion in disturbance operation.

In other words, .

Meanwhile, the lateral slip angular velocity Lt; The steering angle of the driver, Is the steering angle velocity of the controller, Is the sliding angular velocity of the front wheel chassis, and the integral value with respect to time represents an angle.

By the way, ego,

to be.

From this, the lateral sliding angular velocity The steering angle velocity < RTI ID = 0.0 > So that it is the steering angle of the controller.

In other words, By setting Is excluded.

here, Lt; Is a yaw rate reference in a normal driving state in which disturbance does not occur, which is experimentally determined depending on the vehicle.

However, to be.

here, Is the cornering rigidity of the front wheel, Is the cornering rigidity of the rear wheel.

From this Assuming that cos β is sufficiently small, Therefore, .

That is, the steering angle speed of the controller By setting

Sliding angular velocity of front wheel The yaw rate? Is excluded, and as a result, the lateral acceleration a _yp of the vehicle is independent of the yaw rate.

In other words, , Only the motion of the vehicle is left as the motion of the vehicle.

Thus,

And the steering angle of the controller Steering angle velocity ≪ / RTI >

The steering angle velocity in , , γ, etc. are detected from the sensors mounted on the vehicle, , Etc. are determined values.

On the other hand, Lt; / RTI > and Are detected by mounting the two acceleration sensors in the vehicle longitudinal direction, and l _a is a separation distance between them.

Therefore, the present invention can be applied to a steering angle sensor of a controller through a sensor mounted on a vehicle and a calculation means, Get the Target current steering angle And the motor M is applied to the steering shaft 10 to control the yawing motion when a disturbance occurs.

As described above, according to the present invention, the vehicle lateral acceleration, which is a factor of the lateral motion of the vehicle, is related to the lateral slip angle of the front wheel, and by giving the steering angle of the controller that excludes the yaw rate at such lateral slip angle, The yawing motion is suppressed and the running locus is maintained, so that the driving stability of the vehicle is improved.

Claims (1)

Steering angle of front wheel during disturbance during vehicle operation ) Is sufficiently small, the position at which the lateral force of the rear wheel is excluded ( ), The lateral force of the vehicle corresponds to the lateral slip angle of the front wheel The lateral force of the front wheel ) ≪ / RTI > of the vehicle < RTI ID = 0.0 & ), And the lateral sliding angular velocity of the front wheel ( ) Is the steering angle velocity of the driver ) And the steering angle velocity of the controller ( ) And the sliding angular velocity of the front wheel chassis ), And the lateral slip angle ( Is independent of the yaw rate?, The lateral acceleration? ) Is independent of the yaw rate (?), The lateral slip angular velocity The steering angle velocity of the controller in which the yaw rate (?) Component is excluded ), And the integral value thereof is set to the steering angle of the controller ) Of the yawing motion of the vehicle.